Three 10-year-old hippopotamuses perform tricks at a controversial Siberian circus in Russia. Zlat, Yana & Aida are now the stars of the spectacle that organisers say is 'one-of-a-kind' in the world. But, footage filmed inside the circus in Krasnoyarsk shows the animals being forced perform tricks in a setting that is a very far cry from their natural habitat. Hippos are known to be quite aggressive - but these young animals have been trained since they were only 1. Their handler says the show is completely safe for spectators. The circus travels across Russia, Eastern Europe & Asia.